1. Field of the Invention
The invention deals with a light module, notably for a motor vehicle. More particularly, the invention deals with an interior lighting module of the vehicle, such as a roof light or a side fixture, or even a signaling module of the “position” (or “side marker”) type and/or of the “stop” light type for vehicles. Even more particularly, the invention deals with a signaling device generating a depth effect in three dimensions by virtue of a particular optical device. The invention also deals with a signaling device comprising such a module.
2. Description of the Related Art
The patent document EP 1 916 471 A1, which is equivalent to U.S. Publication No. 2008/0094842, describes a rear light of the “side marker” type comprising a cavity formed by a reflector and a screen arranged at a distance from the reflector. The screen has the particular feature of being semi-transparent, which means that a portion of the light rays encountering it is reflected and another portion is transmitted. The cavity exhibits the particular feature that one of the surfaces of the reflector and of the screen which delimit the cavity is dome-shaped. A series of light sources of light-emitting diode type is arranged at the periphery of the reflector and oriented in such a way as to emit the light generally toward the screen. Given the semi-reflecting nature thereof, one portion of the light rays is directly transmitted and one portion is reflected toward the reflector. The latter then reflects these rays toward the screen with an offset directed toward the center of the reflector. These rays reflected by the reflector once again encounter the screen. Like the light rays originating directly from the light sources, a portion of the rays is transmitted by the screen and a portion is reflected toward the reflector, and so on.
The result of these multiple partial transmissions and partial reflections is an optical effect of depth in three dimensions. The lighting or illumination power of the light rays emitted decreases progressively with the ongoing reflections in the cavity. This optical effect is interesting because it allows for a customization of the “side marker” light attracting the attention of other drivers. It also allows for the “side marker” light to be concealed in a bodywork element, such as a motor vehicle bumper or wing. It also allows for the production of a signaling device of small thickness and of small bulk compared to the depth effect generated.
In practice, the semi-transparent nature of the screen is obtained by the application of a metallic covering which can give it a metalized appearance similar to that of a bodywork element. The image formed by this rear light does however exhibit unlit portions. In practice, the areas of transition between the images that are repeated are not lit. From a photometric viewpoint, this means that a not-inconsiderable portion of the outer surface of the light does not participate in the signaling, which can in some cases lead to type-approval difficulties, notably for a “stop” function.
Furthermore, from a viewpoint of style and ability to draw the attention of other road users, it may be desirable to provide images that are less intermittent from a light intensity viewpoint.